Refrigeration system with lube oil separation means



Sept. 27, 1966 J KOCHER ET AL 3,274,796

REFRIGERATION SYSTEM WITH TUBE OIL SEPARATION MEANS Filed Sept. 23, 1965INVENTORF) 52/4/7 J. Koch Ea JO5EPH M Aaw- BY Mama ATTO2NEY$ UnitedStates Patent 3,274,796 REFRIGERATION SYSTEM WITH LUBE OIL SEPARATIONMEANS Erich J. Kocher and .loseph N. Long, both of Milwaukee, Wis.,assignors to Vilter Manufacturing Corporation, Milwaukee, Wis, acorporation of Wisconsin Filed Sept. 23, 1965, Ser. No. 489,611 4Claims. (Cl. 62473) The present invention relates generally toimprovements in the art of refrigeration, and relates more particularlyto the provision of a refrigerating system and apparatus employingimproved instrument-alities for separating entrained oil from the systemrefrigerant and for extracting refrigerant remaining in the separatedoil.

Refrigerating systems of the type to which this invention relatescommonly employ reciprocating compressors to provide high pressurerefrigerant to the system in gaseous state. Normally, oil is employed inthese compressors for cooling and lubricating purposes, the oil beingcustomarily sprayed or splashed about the working parts. Inevitably,some of the compressor lubricating oil becomes entrained in therefrigerant passing through the compressor. If allowed to circulate,this oil reduces the efficiency of the system by coating the variousheat transfer surfaces of the system. The oil also causes maintenanceproblems by congealing in the low temperature portions of the system andclogging check valves and other components.

It is therefore desirable to extract or separate the entrained oil fromthe refrigerant as quickly as possible after compression to minimize theeffects of the oil on other parts of the system. Furthermore, it isdesirable to provide a means in the system to perform as complete aseparation process as possible. This is important not only to keep theoil out of the refrigerant for the aforesaid reasons, but also tomaintain or preserve the lubricating properties of the oil and to retainthe quality and cooling properties of the refrigerant used in thesystem.

Numerous refrigerant systems have heretofore included oil separatingmeans for separating and removing entrained compressor oil from therefrigerant. Such means have, in most instances, consisted of an oilseparator as a separate component in the system as shown, for example,in U.S. Patent No. 3,021,689. In other cases, it has been proposed toincorporate the oil separating means directly in a portion of thecondenser as shown and described in US. Patent No. 3,201,949. Ingeneral, how ever, the oil separating means have consisted of devices ofone type or another employed in conjunction with the condenser of thesystem to separate the oil from the refrigerant either before or afterthe refrigerant is conclensed.

However, in all known prior systems, varying amounts of refrigerantremains commingled with the oil in either the liquid or gaseous stateeven after treatment by such oil separating means. To achieve maximumefiiciency from the refrigeration system and apparatus, it is thereforedesirable to provide a means for extracting this refrigerant tom theseparated oil.

The present invention contemplates the provision of an improvedrefrigerant extraction means and a novel combination of such extractionmeans with other elements of :a refrigerating system.

In addition, the refrigerant extraction means provided by the presentinvention has no moving parts, and therefore requires no maintenance oradjustment for satisfactory operation even for extended operatingperiods.

Furthermore, the refrigerant extraction means of this invention utilizesa heat exchanger to treat the separated oil to extract refrigerantcommingled therewith. More specifically, the improved refrigerantextraction means employs, in one embodiment thereof, the hot, highpressure refrigerant discharged from the compressor to supply thenecessary heat input to the heat exchanger, thereby resulting in anefiicient, simple and economical mode of operation.

The invention may be better understood by reference to the followingspecification and drawing, forming a part thereof, in which:

FIGURE 1 is a diagrammatic part sectional view illustrating thecomponents of a refrigerating system embodying the concept of thepresent invention;

FIGURE 2 is a cross-sectional view of the improved refrigerantextraction means; and

FIGURE 3 is an alternate embodiment of the refrigerant extraction means.

Referring now to the drawing, wherein like reference charactersdesignate the same or similar parts, a typical refrigerating system isshown therein as comprising, in general, a compressor 4, having an inletor suction conduit 6 leading thereto and an outlet or high pressuredischarge line 8 leading therefrom; a condenser 10, disposed in the highpressure discharge line 8; a receiver 12 communicating with condenser 10through conduit 14; and an evaporator or cooling coil 16 having itsinlet end 18 in communication with receiver 12 and its outlet end 20 incommunication with compressor 4 by way of suction conduit 6. As shown,an oil separating means is also provided, and such means is illustratedherein as being embodied directly in the condenser 10 within theentrance section 38 thereof.

Compressor 4 may be of the conventional oil lubricated reciprocatingpiston type, and the condenser 10 may be of the so-called shell and tubetype in which cooling water supplied to conduit connection 22 iscirculated through a plurality of tubes 24, traversing the shell 26between heads 28 and 30. The high pressure discharge line 8 has theusual one-way, non-return check valve 31 therein and a similar checkvalve 32 is interposed in the gravity feedline 14 between condenser 10and the receiver 12. The receiver is also provided with the customaryliquid level indicating gauge 34, and the usual expansion valve 36 isprovided in the inlet to evaporator 16.

The oil separating means of the above described system may, of course,be in the nature of a separate structure but, for the purpose ofillustration, this separating means has been shown and described hereinas forming an integral part of the condenser 10. Thus, while a specificconstruction has been shown in the drawing accompanying and forming apart of this specification, it should be understood that no limitationrelative to the scope of the invention is to be thereby implied.

As illusrated, the condenser 10 includes an oil separating section 38 atits inlet end, such oil separating section being formed by a pluralityof spaced baffles 40 and 42, providing a circuitous path of travel forthe gaseous refregerant and entrained oil discharged by compressor 4through discharge line 8. As the gaseous refrigerant and the entrainedoil enter the condenser 10, they impinge upon the depending baffle 40and are directed downwardly about cooling tubes 24. The gaseousrefrigerant and entrained oil next impinge upon the downwardlyprojecting baflie 42 and are caused to flow in an upward direction aboutcooling tubes 24 before leaving section 38 and entering the main body ofshell 26. By reason of the impingement of the refrigerant vapor andentrained oil upon the baffies and the prolonged period of coolingafforded during the travel of the vapor and oil in its circuitous pathabout the tube 24 within section 38, the oil and the gaseous refrigerantare caused to separate, and the separated oil is confined to section 38by the rbaflie 42.

While the oil separating section 38 separates the major portion of theoil from the refrigerant, a certain portion Patented Sept. 27, 1966conduit 46.

increased temperature due to its compression.

3 of the refrigerant has been found to remain commingled in the oil,either in gaseous or liquid state, in the sump of the oill separatingsection 38. Therefore, in order to more completely separate the oil andthe refrigerant in accordance with this invention, the oil from the oilseparating section 38 of the condenser is passed through a refrigerantextraction means 21, which extracts the commingled refrigerant, returnsit to the refrigerating system, and returns the oil to the compressor 4.

Specifically, the sump of the oil separating section 38 is connected toa float valve chamber 44 by means of a In turn, a float valve 47 in thechamber supplies the separated oil to the refrigerant extraction means21 through conduit 48. Refrigerant extraction means 21 comprises achamber 50 having an inlet from conduit 48, a gas outlet 52, and an oiloutlet 54. Oil outlet 54 may extend upward into the chamber 50, as shownin FIGURE 2, to permit a pool of the separated oil to form in thechamber. Chamber 50 also contains a source of heat. This may, forexample, be an electric heating element 56 (see FIGURE 3), but in thepreferred embodiment, the source of heat may be the discharge line 8,containing hot high pressure gas from the compressor 4. Thus, in FIGURES1 and 2, the chamber 50 has been shown as surrounding or embracing thedischarge line 8 in the nature of a jacket. It will be appreciated thatthe chamber 50, surrounding the discharge line 8, forms, in effect, aheat exchanger in which heat from line 8 is transferred to the contentsof chamber 50-, and the exterior of the conduit 8 at this location maybe provided with fins if desired.

In operation, the compressor 4 provides high pressure, gaseousrefrigerant to discharge line 8. This will be of Additionally, the gaswill have oil from the compressor 4 entrained therein. The gas is forcedfrom compressor 4 through the discharge line 8 to the inlet end of thecondenser 10. As previously described, the inlet of condenser 10includes separating section 38, which removes the major portion of theentrained oil from the gaseous refrigerant prior to condensing therefrigerant to a liquid. This separated oil, along with whateverrefrigerant is commingled therewith, collects in the bottom of oilseparating section 38, and the refrigerant continues its passage throughcondenser 10 and past check valve 32 and then through the refrigerationsystem in the normal manner.

The oil in the bottom of the oil separating section 38 passes throughconduit 46 to the float valve chamber 44. This oil, which is collectedin the float valve body 44, is then conducted by the float Valve 47 tothe refrigerant extraction chamber 50 via conduit 48 and forms a pool inthe bottom of chamber 50, which surrounds the discharge line 8. Theelevated temperature of the discharge line 8, due to the hot compressedgases passing therethrough, heats the separated oil and boils out anyremaining refrigerant therefrom. The refrigerant then passes, in theform of vapor, through conduit 52 to the suction line 6 and hence to theinlet of compressor 4. The oil remains in the jacket 50 until asuflicient quantity has accumulated to overflow through the conduit 52to the oil sump of the compressor 4. The continued heating of the oilduring the period of accumulation in chamber 50 aids in the extractionprocess. It is also to he noted that the oil supplied through conduit 48enters near the bottom of chamber 50, thereby coming into initialcontact with that portion of discharge line 8 closest to compressor 4.Since this is the hottest portion of the line 8, more efficient andcomplete extraction of the commingled refrigerant from the separated oilresults.

A similar operation occurs with the embodiment of the invention shown inFIGURE 3, which may be used to advantage in instances where it isdesired to closely control the amount of heat applied to the separatedoil. The separated oil and entrained refrigerant from the oil separatingsection 38 of the condenser 10 is supplied through conduit 48 to chamber50. The oil then passes over the electric element 56 to extract thecommingled refrigerant from the oil.

It will be appreciated from the foregoing that the present invetionprovides for the effective removal of compress-or oil from the systemrefrigerant by initially providing a means to separate entrained oilfrom the refrigerant employed in the system and thereafter providing ameans to treat the oil to extract remaining commingled refrigerant fromthe oil. Further, the present invention provides an extremely simpleregrigerant extraction means employing, in one embodiment thereof, heatfrom the compressor discharge line. Such use therefore adds to theefficiency and economy of the operation of the refrigeration system.However, if accurate control of temperature is desired, a separateheating element such as that incorporated in the alternate embodiment ofthe invention may be utilized.

Additional embodiments, modifications, and alterations may, of course,be made to the present invention, and it is intended to cover in theappended claims all such variations and modifications as fall within thetrue scope and spirit of the invention.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention:

We claim:

1. In a refrigeration system including an oil lubricated compressorhaving a hot gas discharge conduit communicating with a condenser, meansassociated with the inlet to the condenser in communication with the hotgas discharge conduit for initially separating oil from the refrigerantemployed in the system, an extraction chamber surrounding a closedportion of said hot gas discharge conduit between the compressor andsaid initial oil sepa rating means, whereby said discharge conduitprovides a heating element for said extraction chamber, and a conduitcommunicating between said initial oil separating means and said chamberfor conducting the initially separated oil having residue refrigeranttherein to said chamber, whereby said heating element provides heat forextracting residue refrigerant from the oil, said chamber also having aconduit communicating therewith for discharging refrigerant therefromand a separate conduit communicating therewith for discharging oiltherefrom.

2. A refrigeration system according to claim 1, wherein the initial oilseparating means is formed in the inlet end of the condenser and theconduit for discharging refrigerant from the extraction chambercommunicates with the upper portion of said chamber, while the conduitfor discharging oil from said chamber extends upwardly from the bottomand into communication with an intermediate portion of the interior ofsaid chamber.

3. A refrigerating system according to claim 1, wherein the conduit fordischarging refrigerant from the extraction chamber communicates withthe low pressure inlet side of the compressor while the conduit fordischarging oil from the extraction chamber communicates with thecompressor crankcase.

4. In a refrigerating system including an oil lubricated compressorhaving a hot gas discharge conduit communicating with a condenser, meansassociated with the inlet to the condenser in communication with the hotgas discharge conduit for initially separating oil from the refrigerantemployed in the system, a tilted extraction chamber having athermostatically controlled heating element projecting therein from oneend thereof, a conduit communicating between said initial oil separatingmeans and said extraction chamber above said heating element forconducting the initially separated oil having residue refrigeranttherein to said chamber, a conduit communicating between said chamberand the low pressure inlet side of said compressor for dischargingrefrigerant from said chamber and conducting the same to said lowpressure inlet, and another conduit communicating between saidextraction chamber and the compressor crankcase 6 for conductingrefrigerant-free oil from said chamber to FOREIGN PATENTS the compressorcrankcase.

622,043 4/1949 Great Britain.

References Cited by the Examiner UNITED STATES PATENTS Philipp 62 472 XW. E. WAYNER, Assistant Examiner.

Obreiter 62-83 Honegger 62--473 X 5 ROBERT A. OLEARY, Primary Examiner.

1. IN A REFRIGERATION SYSTEM INCLUDING AN OIL LUBRICATED COMPRESSORHAVING A HOT GAS DISCHARGE CONDUIT COMMUNICATING WITH A CONDENSER, MEANSASSOCIATED WITH THE INLET TO THE CONDENSER IN COMMUNICATION WITH THE HOTGAS DISCHARGE CONDUIT FOR INITIALLY SEPARATING OIL FROM THE REFRIGERANTEMPLOYED IN THE SYSTEM, AN EXTRACTION CHAMBER SURROUNDING A CLOSEDPORTION OF SAID HOT GAS DISCHARGE CONDUIT BETWEEN THE COMPRESSOR ANDSAID INITIAL OIL SEPARATING MEANS, WHEREBY SAID DISCHARGE CONDUITPROVIDES A HEATING ELEMENT FOR SAID EXTRACTION CHAMBER, AND A CONDUITCOMMUNICATING BETWEEN SAID INITIAL OIL SEPARATING MEANS AND SAID CHAMBERFOR CONDUCTING THE INITIALLY SEPARATED OIL HAVING RESIDUE REFRIGERANTTHEREIN TO SAID CHAMBER, WHEREBY SAID HEATING ELEMENT PROVIDES HEAT FOREXTRACTING RESIDUE REFRIGERANT FROM THE OIL, SAID CHAMBER ALSO HAVING ACONDUIT COMMUNICATING THEREWITH FOR DISCHARGING REFRIGERANT THEREFROMAND A SEPARATE CONDUIT COMMUNICATING THEREWITH FOR DISCHARGING OILTHEREFROM.